title: High performance liquid chromatographic determination of methylxanthines in canine serum, gastric and pancreatic juices.
abstract: A convenient high performance liquid chromatographic method for the determination of methylxanthines in biological samples is described. Separation was achieved by reversed phase chromatography using a mobile phase consisting of tetrahydrofuran + methanol + 0.01M potassium dihydrogen phosphate, pH 3.5 (1:20:79, v/v/v), on a 7 microns C18 column and a C18 Lichrosorb precolumn at a flow rate of 0.8 mL/min. Levels varying from 0.25-16 mg/L could be detected by UV at 280 nm. In this range, standard curves were established for 4 methylxanthines: theobromine, paraxanthine, theophylline and caffeine in 4 media: mobile phase, serum, gastric and pancreatic juices, and were found to be linear (r greater than or equal to 0.9975). Overall characteristics of the method were determined as: percent recovery (89.54%), accuracy (greater than or equal to 99.4%) and reproducibility (greater than or equal to 95%). Retention times ranged from 4.21 +/- 0.01 (1-methyluric acid) to 10.8 +/- 0.03 min (caffeine). Animal experiments (5 and 10 mg/kg boluses) were used to determine caffeine half life in dog's blood (310 +/- 46 and 453 +/- 59 min, respectively) and its secretion into pentagastrin stimulated gastric juice (mean concentrations 2.51 and 6.04 mg/L; mean outputs 351 and 1206 micrograms/2.25 h; both statistically different at p less than 0.001 level).
authors.affiliation: INSERM, Marseille, France.
authors.forename: P
authors.initials: P
authors.lastname: Casoli
authors.forename: H
authors.initials: H
authors.lastname: Vérine
mesh_terms: D000818:Animals; D002110:Caffeine / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D005750:Gastric Juice / Q000737:chemistry*; D006207:Half-Life; D007202:Indicators and Reagents; D010189:Pancreatic Juice / Q000737:chemistry*; D014970:Xanthines / Q000032:analysis* / Q000097:blood
chemical_list: D007202:Indicators and Reagents; D014970:Xanthines; D002110:Caffeine